AWS: Handle kube-down case where the LaunchConfig is dangling

cluster/aws/util.sh

@@ -1345,6 +1345,11 @@ function kube-down {
       done
       echo "All instances deleted"
     fi
+    if [[ -n $(${AWS_ASG_CMD} describe-launch-configurations --launch-configuration-names ${ASG_NAME} --query LaunchConfigurations[].LaunchConfigurationName) ]]; then
+      echo "Warning: default auto-scaling launch configuration ${ASG_NAME} still exists, attempting to delete"
+      echo "  (This may happen if kube-up leaves just the launch configuration but no auto-scaling group.)"
+      ${AWS_ASG_CMD} delete-launch-configuration --launch-configuration-name ${ASG_NAME} || true
+    fi
 
     find-master-pd
     find-tagged-master-ip